libressl: security bump to version 2.7.4

Fixes CVE-2018-0495: ECDSA signing side-channel attack.

Cc: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit b609ee33e1d2d37711722933bad279df3bed2786)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libressl/libressl.hash

@@ -1,4 +1,4 @@
 # From https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/SHA256
-sha256 917a8779c342177ff3751a2bf955d0262d1d8916a4b408930c45cef326700995  libressl-2.7.2.tar.gz
+sha256 1e3a9fada06c1c060011470ad0ff960de28f9a0515277d7336f7e09362517da6  libressl-2.7.4.tar.gz
 # Locally computed
 sha256 5c63613f008f16a9c0025c096bbd736cecf720494d121b5c5203e0ec6e5955b1  COPYING

package/libressl/libressl.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-LIBRESSL_VERSION = 2.7.2
+LIBRESSL_VERSION = 2.7.4
 LIBRESSL_SITE = https://ftp.openbsd.org/pub/OpenBSD/LibreSSL
 LIBRESSL_LICENSE = ISC (new additions), OpenSSL or SSLeay (original OpenSSL code)
 LIBRESSL_LICENSE_FILES = COPYING